I have 250 GB HDD. I have created 5 partitions of it. Unfortunately, I am unable to format, delete, access my 5th partition which is of 15 GB. It says that it is Unallocated. If it is unallocated then why It is not "format-able", "delete-able" and inaccessible. I am using Linux Ubuntu. Also, I checked it in Windows 7 and Windows 8, but it was inaccessible at all. If there are bad sectors in that partition then how can I fix them without losing any data from other partitions so that partition can be accessible.